Electric furnace.



PATENTE!) APR. 9o, 19m,

ELECTRIC FUBNGB.

Mummia# Pimm JULY 1-. 1905.

fffffff In /NvENTo/i'l f urn 'l diil'erence of potential between the resistance Lt, and communicated to its environment is sulliciently high, current will leak across lrom aparticularly satisfactory form for gas rc` sistance, 4, composed ot' carbon, iridium or actions for which this type ol'l furnace is in general especially well adapted.

',lo render my invention clear to those skilled in the art, li have illustrated certain embodiments in the accompanying drawings,

rigs. i, a, 4, 5, c, 7, s, a, ie, n, 12, i3, 14 and 15. it will be understood that these drawings are to a hrgc extent diagrammatic, such obvious and subordinate details as terminal constructions, packing, housings, etc., being omitted, as' their torni and application can be appreciated by reference to publications, inparticular to my former Letters iaten t referredto above.

in the Iirst ligure ol'I the drawing, 1 represents a suitable source of current connecting throughv leads 2 and 3 with a heating rereiractory dry electrolyte, either solid or i fused. e. conductor, 5, also of anyrelractorji' i material is arranged in general parallel to and at a short listancefrom the resistance 4, if, now, a current be passed through the resistance 4.-, there will be a potential drop between the points 6 and 7 of the rod 4, which points lie opposite the ends of the conductor 5. The rod 5 will beat the same potential throughout as long as it does not carry current. Vlhere will, therefore, be set up, a

4 and the conductor 5, which will vary from point to ypoint along the conductor 5. It the temperature produced in the resistance the resistance ilY to theconduotor 5 and after Yihnving a distance in the conductor will leak back again to the resistance, thus traversing thc. intervening vapor or gas; By bending 'the em'iductin t ol Fig. 1 into a loop, as shown in Fig. 2,-the points of dill'erent potential represented by 6 and 7 may be brought close together and the conductor 5 `will be superlluous, the leakage taking place directly between the points (i and 7. This analogous to the leakage under conditions of high vacuum in certain incandescent lamps. instead oll bending the conductor 4, the points (i and 7 olI ditl'erent potentials may be brought closer together by making part ot the conductor 4 ot' relatively smaller diam-l senesi eter shown in Fig. 3; here the leakage crurent will flow parallel to and-around the contracted portion of the part 4. `This idea may be applied to a porous or granular or powdered conductor, for if We consider two contacting grains, as in Fig. 4, Where they are shown greatly magni'lied, it is clear that the` grains, and 7, together constitutes the electrically uninterrupted conductor 4: ofthe former igures. They contact'over a small area and approach closely, but do notcontact at other places, thus We have the condi=- ol Fig. 1 is modified by developing the conducting resistance 4 into a tube 'surrounding the rod conductor 5, while in Figf the cond uctor 5 becomes a tube surrounding the resistance 4. Tt is clear that if for any reason adjacent portions of'the elements '4 and 5 should be held at the same potential, this may be accomplished by connecting thein by a non-gaseous conductor instead of through a gas or vapor. ln Fig. 7 the construction illustrated' in Fig. 'l is shown with such modification. c ln the foregoing, the di'il'eren'ce of potential maintaining the gapcurrent has not exceeded that cnn'doycd in heating the resistance 4. However, such a limitation is not necessary. nor is it necessary that the same kind ocurrent be used for the gap 'and the -heating resistance 4. `For example, in Fig. 8, l show a modification of the construction shown in Fig. 5, wherein an alternating current is em.- ployed to heat'v the part 4', and a direct current is maintained across the gap. ,'lhe alternating current source `is shown at 2l, and at l22 and 2?, respectively, appear the primary and secondary of a transformer. The source of direct current is indicated at 24; and a regulating resistance at 25.

itis not always desirable to have the heating resistance 4 constitute on electrode 'of the gap. For instance, it often desiralile to make the part 4 of carbon and line it with a refractory lining to prevent carbon vapors within the tube. ln such a case the eleotrodes may be iridium or electrolylic conductors arranged as shown in Fig. E). Here .8 and are gap electrodes with a source ol' voitage I() and a regulator 8l. A lining lior the heating uar 4 is shown at l(). lt'is sometimes an advantage to make th l area ol' the conducting gap large and tlsx current density therein fairly even. This isacconiplishcd by producing praciicfilly a fixed drop '.:crossnll portions ol` an equally long gap as shown in Vig. ll).

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. In 11 is shown an arrangement Wherein the heating function oi" the part 4 is performed by an oxygen fed llame; This arrangement is particularly advantageous in r places Where iridiuin is heated as it has been observed that 'this expensive materialWastes away milch quicker Wl'ien heated electrically than when heated to the same temperature l by a lan'le. At 11 appears the outer furnace ro Wall; at 12, the burner; and at 26 iridiuni tube. lt is advantageous, where extremely high temperatures are required, to produce the heating by an are, instead of by gas or resistance heating ol solid or liquid conductors. Such an a`rc-heated gap is lshown in i" Fig. 1.2, which is a Moissan furnace with a tuhe, 1.6, oi carbon, withinv being the gap electrode 8, the tube constituting the electrode 9, as in Tdigs. 10 and 1 1. There is still 2o another variation of the idea, introducing the element of time, whereby, during an interval,

heat is stored until a sullieient temperature is reached, -then thc-healing current interrupted and a gap intri'rduced, supplied with a z5 small potential dill'eronce not sullicient to produce a current to maintain the temperature. As long as the temperature remains high, current will pass and will cease unless,

after a little more heat is supplied. Such a 3o device is shown in Figs. 13 and 14. Here the,

gap electrodes 8 and 9 are shaped like' parts ot a valve and are Shown in contact, current traverses then). and the contact, heating them. If, nowf, the potentialbe, let us say,

3 5 ten volts, and/a'current of gas he forced up- Ward through the electrodeI 9, the electrode S may be raised, producing a gap across which.

current Will` flow While all remains hot. By arranging the gas pressure and gas friction `in 4o the'tuhes properly, a stuttering opening and closing ol' the contact between the electrodes will he etl'cct'ed and the gases passing sulnnitted td the el'ectrolyzing action olj the electric `ap current. By the additioii of a coil, 32,

possessing sell-induction, in'series with the electrodes, the current across the gap can he ipcreascd by thc coil discl'iarge at each lni'lr, when direct current is employed for operating the furnace. -Care must be exer .5o cised, hon'eyer. not t i) use enough self-induction t i'produ.cc.a "constrictedvarc or spark discharge aero ie gap, as such a discharge would he local anrhniueh of the passing `would not he subjected to the electrolyzing sanction L Up to this point, l have described relative arrangements of parts. ,It remainsto show more specifically how'such furnaces are con .trolled. There are several factors conspiringi 6o to produce a given condition and ingeni'al a change in any of the factors will ejl'ect, the resultant condition produced hy all together. lt is clear that the auxiliary heat can he controlled by neiilating the current-through 6J the resistance 4 in F15. 5, or through the arc in Fig. 12, or the gas supply in Fig. 1 1. lt is also clear that the ga p potential Ycan he controlled in Figs. S, Si, 1U, l1 and 12. 'lhe area of the gap can he varied in Figs. l() and l1 hy pushing the eleetnidc more or less into electrode i). 'lhc' length of thc gap can he \f'aried in Fig. t) hy moving cithcr clccirodc, S or i), axially rclatiyc to its cooperating inem* ber. ln Figs. 13 and. 1st, the period olvihraR tion of the electrode can he inodiicd hy controlling the gas pressure as slated and the activity ot the gap current increased hy increasing the. self induction o1' the circuit, in-

cluding the electric source, 32;, thc regulator,

341-, and the electrodes .)kand A. tui-ther n'iodiiication can he oiiectcd hy shuuting the gap 5.4) as shown in lFig. 15. in the case of a furnace such as illustrated in `Fig. 11 or Fig. 1Q, the action is greatly aIlc-ctcd by hloiving a` gas or n'iixturc of gases or vapors through the tube i). Such 'a gas cools the gap and where a reaction is produced the coolingdepends not only on the initial and end temperature ot the gas, but also on the energy absorbed or set vlree by the reaction itself. All i'nethods ol control ali'eet the di inensions of the gap, the temperature ol' the gap, or the electric tall of potential across the gap kand any agency which all'ects any ol' these may serve as a control.

What has been said in the foregoing conu eerning the thernii :ally ind need. eoiulucti'vity of the gap and the passage theretlnough. ot

current under moderate diiiiirenccs el' potential must not hc taken to exclude troni inv l invention the conlhinz'ition ol a gap, a source ol high temperature al'ccting the gap and a current across said gap under a dillerence ol.'- potential as high or higher than that ncccssary to maint-ain an arc. The auxiliary heat need not heconie unimportanteven under these conditions as its cll'cct is 'to steady and expand the arc and to 'allow it to be lengtlicned .more than otherwise possible. The tendency to constriction is reduced. and in general the volume ol the are materially increased se that the current tends to flow between the electrodes, as if they were inimersed in a conducting liquid. The teinperature gradients are naturally less steep in such an are and it is therefore, preferable where reactions are desired, Whichare reversed by excessive temperatures.

Fig. 16 represents a n'iodilication of the device shown in Fig. 4, thc material in this in.- stance being represented as porous.' Such a n'laterial serving the conditions required in thateit has surfaces ot different potential at lligli temperature and near together. iissuming that the porous niaterial is in the forinpf a tube gases niightenter the inside of the tilbemand be subjected to clectrili'cation at high temperature in j'iassing through theI pores and. might then pass out to a collecting device.

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rl`lie furnace herein described may be used under conditions of pressure above or below'.

tion Serial Number 166,669, i'iled July 23 i903, of which application the present application is a division, claims are made upon certain iiiethcds of operation described herein l claim as my invention,

l. .ln a furnace of the character described, means for heating;- the furnace body, and means for supeiposiiil in the furnace the heat of an electric are or con ducting gap.

ln an electric furnace, a conducting re sistance constituting the bodyof the furnace, incaiisfor applying electrical energy to the said resistance, aiid one or more auxiliary electrodes adapted to constitute the terminal or terminals of a conductin r gap in operative relation to tho furnace body.

3. in au electric furnace, a conductiiucr resistance constitutingA the body of the furnace, .means f( applying electrical energy to the said resistance, and one or more auxiliary electrodes adapted to constitute the terminal or terminals of a conduct-ing gap in the fur.- iiace body.

4. ln an electric furnace, a conduct-ing resistaiice constitutiiiga portion of the electric circuit, an auxiliary or supplemental electrode constituting one terminal of a conducts ing' gap inside the furnace body, and means for causing current .to 'How 'through the said conducting resistance and through the conducting gap.

5,. an electric furnace, a source of heat for the furnace, a pair :of electrodes, and means for passing current across a gap ,be-

Atween the same, in combination with means for Varying the dimensions of the gap.

6. lin an. electric furnace, two sources of heat, enclosing applied to the furnace itself and the other being derived from an electric .current passingbetween suitable electrodes,

e in combination with means fdr varying the said current. 'l

trodes, and means forpassing current across gap between the same, in combination with :in auxiliary source of heat, and means for Varying the temperature produced by the said auxiliary heat source.

S. ln an electric furnace, a pair of electrodes, means for passing current across a gap between the saine, in conjunction with c second .or auxiliary source of heat, and means for causing alcurrent of gas to How at Varying speeds past the said gap.

Q. An electric furnace, consisting of a heating conductor iii two parts, together with means for causing an oscillatory contact and separation between the two partsof the heat* ing conductor, so that during the periods of separation an electric current passes across the gap under the combined influence of a high temperature and a difference of potential.

l0.' Anelectric furnace, consisting of a tu bular conductor, closable by a second con- 'ducten an electric current through the two conduct ers, whereby they are highly heated, togetherwith a current of gas through the tubular conductor causing alternate opening 'and closing of the said tubular conductor due to relative movements of the two conductors.

11. An electric resistance and gap furnace li airing conductors carrying a heating current, means for passing electric current through the electric resistance and thereby developing one source of heat, means for passing current across' the gap and thereby developing another source of heat, and means for alternately' openingand closing the said gap. l

Signed at New York, in the county of New .Yorln and State of New York, this 30th. day

of June A. l). 1905. A

HENRY NOEL POTTER.. ldlitnesses:

WM. H. CiiPnL, Gnomes H. Srociisninon.I

7. ln an electric furnace, suitable elec-Y 

